A shaft sealing device is provided around a rotor in a rotating machine, such as a gas turbine or a steam turbine, in order to reduce the leak amount of a working fluid that flows from a high-pressure side to a low-pressure side. As an example of this shaft sealing device, for example, a shaft sealing device described in the following Patent Document 1 is known.
This shaft sealing device includes a housing provided at the stator, and a seal body including multiple thin plate sealing pieces.
In the seal body, the multiple thin plate sealing pieces are stacked with small clearances between each other such that the thickness direction of each thin plate sealing piece is directed to the circumferential direction of the rotor. The respective thin plate sealing pieces are obliquely arranged so that the end portions (tips) of the thin sealing pieces on a radial inner side are located further toward a forward side in the rotational direction of the rotor than the end portions (rear ends) of the thin sealing pieces on a radial outer side, the rear ends thereof are coupled to each other at the rear ends thereof, and the tips of the thin sealing pieces are free ends.
In the shaft sealing device schematically configured in this way, the tip of each thin plate sealing piece comes into contact with the rotor when the rotor remains stationary. If the rotor rotates, the tips of the thin plate sealing pieces are lifted from the outer periphery of the rotor by a dynamic pressure effect produced by the rotation of the rotor, and are brought into non-contact with the rotor. For this reason, in the shaft sealing device, wear of each thin plate sealing piece is reduced, and the service life of a seal becomes long.
Additionally, in the above-described mechanism, one axial end portion of the seal body on a fluid low-pressure region side in an axial direction is covered with a low-pressure side plate, and the other axial end portion of the seal body on a fluid high-pressure region side in the axial direction is covered with a high-pressure side plate. Also, the flow of the working fluid to the small clearances between the thin plate sealing pieces is regulated by the low-pressure side plate and the high-pressure side plate.
Here, the low-pressure side plate and the high-pressure side plate are usually segmented into a plurality of portions in the circumferential direction and are disposed with segmentation clearances between each other.